1. Field of the Invention
This invention pertains to the field of electricity. More particularly, this invention pertains to measuring and testing of electrical parameters. In still greater particularity, the invention is directed to the measurement of electrical energy per se. By way of further characterization the invention the invention will be described as it pertains to a phase noise analyzer.
2. Description of the Prior Art
In the field of electronic design and engineering it is oftentimes necessary to determine the purity of a microwave signal source. The variation in amplitude, frequency, and phase of such a signal is affected by circuit design and performance. Each variation is measurable and each has instrumentation techniques to provide the circuit designer or evaluator a quantitative indication of the degree of presence of the variation. Some types of signal variation or distortion are more easily detected than others.
A particularly troublesome signal parameter to instrument is the presence or degree of presence of phase noise. This type of distortion is characterized by the presence of discrete frequency bands displaced from the frequency of the signal of interest. When present, these spurious frequency bands are measured relative to the amplitude and frequency of the desired signal. The percentage of the spurious signal being a figure of merit for the circuit design.
Past measurement efforts have involved isolation of the spurious signal, measurement of the amplitude of that isolated signal, measurement of the amplitude of the desired signal, and calculation of the value. Prior to making this invention, the inventors were unaware of any instrument able to perform this measurement directly. Although a variety of noise analyzers and jitter measuring devices were known none was available to measure this design parameter in a quick and simple fashion.